mineral

Yellow chalcedony (likely heat-treated or resin-coated)

Microcrystalline quartz, SiO₂

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent honey-yellow color with a waxy to glassy luster and no visible cleavage. The irregular shape and smooth fracture resemble chalcedony, though the bright surface may indicate treatment or an amber-like material.

Identified August 8, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater deposits microcrystalline quartz in cavities and fractures, commonly in volcanic rocks. Its exact geological age cannot be determined from the photograph.

Uses & applications

Used for cabochons, carvings, beads, and ornamental objects; common pieces have modest value. If actually amber or treated material, identification and value differ substantially.

Geological facts

Chalcedony is cryptocrystalline quartz composed of interlocking quartz fibers and commonly occurs in agates and geodes. Yellow coloration may result from iron-bearing impurities, heat treatment, or dye.

Field identification & locations

Test with a steel file or streak test only if damage is acceptable: true chalcedony resists scratching and leaves a white streak; amber is much softer and may float in salt water. Common sources include Brazil, Uruguay, India, Madagascar, and the United States.